forked from Apple-2-HW/Apple2-IO-RPi
49 lines
1.3 KiB
QBasic
49 lines
1.3 KiB
QBasic
1000 PRINT "Slot number? "
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1010 INPUT S
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1015 REM Set up InputByte, OutputByte, InputFlags and OutputFlags
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1020 IB = 49294 + S * 16
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1030 OB = 49293 + S * 16
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1040 FI = 49291 + S * 16
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1050 OF = 49287 + S * 16
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1060 POKE OF,15: REM set to bank zero with flags high
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1070 GOSUB 2000
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1999 END
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2000 REM Execute Command
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2010 PRINT "$";
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2020 INPUT CM$
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2030 A = 5: GOSUB 8000: REM ExecCommand
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2040 FOR X = 1 TO LEN (CM$)
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2050 A = ASC ( MID$ (CM$,X,1))
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2060 GOSUB 8000
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2070 NEXT
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2080 A = 0: GOSUB 8000
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2100 GOSUB 9000
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2101 PRINT CHR$ (A);
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2110 IF A = 0 THEN RETURN
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2130 GOTO 2100
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7000 REM Get Flags
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7010 F = PEEK (FI)
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7020 RF = 0
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7025 WF = 0
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7030 IF F > 128 THEN WF = 1:F = F - 128
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7040 IF F > 64 THEN RF = 1
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7050 RETURN
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8000 REM Send Byte
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8010 GOSUB 7000: REM Wait for read flag low
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8020 IF RF = 1 THEN GOTO 8010
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8030 POKE OB,A
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8040 POKE OF,14: REM Set write flag low
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8050 GOSUB 7000: REM Wait for read flag high
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8060 IF RF = 0 GOTO 8050
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8070 POKE OF,15: REM Set flags high
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8080 RETURN
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9000 REM Get Byte
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9010 POKE OF,13: REM Set read flag low
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9020 GOSUB 7000: REM Wait for write flag low
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9030 IF WF = 1 THEN GOTO 9020
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9040 A = PEEK (IB)
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9050 POKE OF,15: REM Set flags high
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9060 GOSUB 7000: REM Wait for write flag high
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9070 IF WF = 0 THEN GOTO 9060
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9080 RETURN
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